1. Field of the Invention
The present invention relates to a semiconductor device, and more particularly, to a method of manufacturing a non-volatile memory.
2. Description of Related Art
As the name implies, memory is a semiconductor device designed specially for storing data or codes. As the functions provided by a computer microprocessor are increasingly powerful and the amount of programming and computation in most computer software continues to increase, memory with larger storage capacity is urgently needed. In order to fabricate cheaper and larger capacity memory, the techniques and processes of fabricating memory devices is the driving force behind the challenge of pushing semiconductor technologies toward a higher level of integration.
Non-volatile memory is a type of memory device that allows multiple data writing, reading and erasing operations. Furthermore, the stored data will be retained even after power to the device is removed. With these advantages, non-volatile memory has been broadly applied in personal computer and electronic equipment.
At present, one of the more commonly used memory array structures includes the NAND type array structure. Because the NAND type array structure mainly contains a serially connected memory cells whose programming and erasing operations are carried out together, a memory cell array fabricated as a NAND type array structure is able to increase the packing density of devices and ultimately their level of integration.
With the rapid development of fabrication processes and the continuous reduction of device dimensions, the space between the NAND type array structure and various memory cells is being shrink correspondingly. However, due to the limitation of the process window in photolithographic and etching processes, it is very difficult to fabricate a product that meets the required memory cell size and spatial separation between memory cells. Furthermore, in a subsequent process, the slight shrinkage of size that leads to a relative shrinkage of the space between the memory cells can lead to additional problems. For example, when filling the space between various memory cells with an insulating material, the insulating material layer inside the space may form voids or the insulating material may be prevented from filling up the space. Consequently, the reliability of the process is questionable.